German Patent Application P 24 13 935.3, corresponding to Ralph Schmiechen et al., Ser. No. 560,193, filed Mar. 20, 1975, now U.S. Pat. No. 4,012,495, which is incorporated herein by reference, describes racemic and optically active 4-(polyalkoxyphenyl)-2-pyrrolidones of the formula ##STR3## wherein
R.sub.1 and R.sub.2 are identical or different and are hydrocarbon of up to 18 carbon atoms or alkyl of 1-5 carbon atoms substituted by one or more halogen, hydroxy, carboxy, alkoxy, alkoxycarbonyl, carboxamido, or optionally substituted amino, or R.sub.1 and R.sub.2 collectively are alkylene of 1-3 carbon atoms;
R.sub.3 is hydrogen or methoxy;
R.sub.4 is hydrogen, alkyl, aryl, or acyl; and
X is oxygen or sulfur, and processes for the preparation thereof.
It has now been found that 4-(polyalkoxyphenyl)-2-pyrrolidones of the above formula wherein R.sub.4 is --CO--R and R is O-alkyl, O-aryl, O-aralkyl, NH.sub.2 --, NH-alkyl, NH-aryl, NH-aralkyl, N(alkyl).sub.2, N(aryl).sub.2, and ##STR4## HAVE THE SAME PHARMACOLOGICAL SPECTRUM OF ACTIVITY, BUT PRONOUNCEDLY MORE PROTRACTED EFFECTIVENESS.
Reference is also made to Ralph Schmiechen et al., Ser. No. 659,082, filed Feb. 18, 1976.